[Embargoed for release until 9 p.m. ET Wednesday, March 16, 2005,
to coincide with a presentation at the annual meeting of the American
Chemical Society.]

DESERT PLANT MAY HELP TREAT INSIDIOUS TROPICAL DISEASES

COLUMBUS, Ohio -- Plants native to the Mojave Desert may one day help
provide relief to millions of people who suffer from two prominent tropical
diseases.

Karl
Werbovetz

Scientists at Ohio State University found that extracts of the dotted
dalea (Psorothamnus
polydenius) and the Mojave dalea (Psorothamnus arborescens)
can kill the parasites, which are a kind of protozoa that cause the diseases
leishmaniasis and African
sleeping sickness. While both diseases are rare in North America,
they are prevalent in dozens of countries worldwide, particularly developing
nations. If left untreated, the diseases can be fatal.

"Most of the available drugs are given by injection over
a long course of time," Werbovetz said. "We're hoping
to develop those extracts into effective compounds that are cheap
and readily available, and that can be taken by mouth."

"At last count,
about 700 of our soldiers had the disease. It's not an illness that
people die from, and the troops can still perform their duties.
But it does leave scars and can also make a person prone to infection."

Werbovetz conducted the study with Manar Salem, a doctoral candidate
in medicinal chemistry and pharmacognosy. The two presented their findings
on P. arborescens on March 16 in San Diego at the national meeting
of the American
Chemical Society. Their findings on P. polydenius appear
in a recent issue of the Journal
of Natural Products.

The researchers first screened hundreds of plant extracts to see which,
if any, would kill Leishmania
donovani and Trypanosoma
brucei, the parasitic protozoa that cause leishmaniasis and African
sleeping sickness, respectively. Leishmaniasis is transmitted by sand
flies, while African sleeping sickness, or African trypanosomiasis, is
transmitted by the tsetse fly.

The researchers conducted laboratory tests to determine which plant extracts
would kill the protozoa but not harm healthy kidney cells cultured from
the African Green Monkey.

Extracts from these related plants were among the best inhibitors of
parasite growth while showing lesser effects on the kidney cells.

While there are several forms of leishmaniasis, the most common
forms affect the surface of the skin (cutaneous leishmaniasis)
or the internal organs (visceral leishmaniasis). Cutaneous leishmaniasis
causes open sores and raised boils on the skin, while visceral
leishmaniasis invades the liver and spleen and causes these organs
to swell. People with the visceral form of the disease develop
anemia and also lose a significant amount of weight. Visceral
leishmaniasis is fatal in 90 percent of all cases left untreated.

About 2 million new cases of leishmaniasis are reported each year, according
to the World Health Organization (WHO).
Of those, at least half a million are visceral leishmaniasis. The disease
is found in Mexico, Central and South America, Southern Europe, Asia,
the Middle East, and Africa.

Also, several hundred U.S. soldiers stationed in the Middle
East have developed cutaneous leishmaniasis.

"At last count, about 700 of our soldiers had the disease,"
Werbovetz said. "It's not an illness that people die from,
and the troops can still perform their duties. But it does leave
scars and can also make a person prone to infection."

Sleeping sickness affects people in mostly rural areas of
sub-Saharan Africa. The disease usually begins with a high fever,
a rash and swollen glands and, if left untreated, can progress
into the brain, where it causes inflammation, coma and, eventually,
death.

"The primary drug used to treat African sleeping sickness
kills 5 percent of the people who take it arsenic is one of
its main ingredients," Werbovetz continued. "But left
untreated, the disease kills 100 percent of those infected."

However, not only are the drugs used to treat African sleeping
sickness expensive, they're not available everywhere they are
needed.

According to the WHO, African sleeping sickness threatens
over 60 million people in 36 countries of sub-Saharan Africa.
Estimates on how many people develop the disease annually vary
anywhere from 50,000 to 500,000, Werbovetz said.

"Real estimates are virtually impossible to come up with
because of the rural nature of this disease," he said.